Method of installing coiled tubing with a plurality of integrated large diameter external assemblies

ABSTRACT

A method of installing a coiled tubing string having a plurality of external assemblies includes injecting the coiled tubing string into a well with a coiled tubing injector, when a first external assembly on the coiled tubing string reaches the coiled tubing injector, transferring support of the coiled tubing from the coiled tubing injector to a coiled tubing snubber located below the coiled tubing injector, opening the coiled tubing injector to an extent sufficient to allow passage of the first external assembly thereby, and actuating the coiled tubing snubber to move the first external assembly past the coiled tubing injector. The first external assembly has an outside diameter that is larger than an outside diameter of the coiled tubing string.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is claims priority to U.S. Provisional Patent Application No. 62/192,753, filed on Jul. 15, 2015, entitled “METHOD OF INSTALLING COILED TUBING WITH A PLURALITY OF INTEGRATED LARGE DIAMETER EXTERNAL ASSEMBLIES,” which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the completion of oil and gas wells using coiled tubing. More particularly, embodiments of the invention relate to a method and related apparatus for injecting coiled tubing strings into wells having positive wellhead pressures.

BACKGROUND OF THE INVENTION

Equipment used to insert coiled tubing into an oil or gas well with positive wellhead pressure requires that the tubing be of a continuous outside diameter, therefore negating the ability of integrating external assemblies that are of a greater outside diameter than the coiled tubing diameter.

One existing solution involves utilizing commercially available external assemblies placed within a pressure containing housing installed above the wellhead and blow out preventer (BOP), then using the conventional coiled tubing handling equipment consisting of a coiled tubing injector (CT injector) and pressure containing stripper to feed the coiled tubing through these external assemblies, and then affixing those external assemblies to the coiled tubing at the desired locations. This process, however, requires that the coiled tubing be of a small enough outside diameter to feed through the inner bore of these external assemblies.

One example of a commercially available external assembly having an inside through bore diameter that is greater than the outer diameter of the coiled tubing is a seal element commonly known in the oil tools industry as a “packer”. There may be other types of oil and gas well tools that have a through bore diameter that is greater than the outer diameter of the coiled tubing, such as well logging tools or well environment monitoring tools.

Commercially available packers may be installed at various locations along the length of a CT string by stacking these packers within a pressure containing housing above the wellhead and blow out preventers, and below a conventional CT injector. Using the CT injector, the CT string is forcefully inserted through the inner bore of these packers and through to the BOPs and wellhead and into the oil or gas well. When the installation location on the CT is reached. The CT injection is stopped, the BOP is closed, the pressure is vented from the pressure containing housing containing the packers, and the housing is opened to expose the packer(s). The packers are then affixed to the CT string using a mechanical device. An example of this system is offered by Select Energy and sold under the trade name “Mighty-Mite” packers.

U.S. Pat. No. 6,328,111 to Bearden et al. discloses a form of snubbing system for the purpose of installing an electric submersible pump (ESP) into a well having a positive wellhead pressure. The snubbing system thereof is designed to engage directly onto the ESP which is located on the distal end of either a jointed tubing string or coiled tubing string and is attached after the CT is inserted into the pressure containing housing (aka lubricator) using a conventional CT injector. This aspect of the installation method, however, only applies to assemblies that are on the distal end of the coiled tubing and will not function if the external assembly is located away from the distal end of the coiled tubing.

In view of the above, there is a need for a method and related apparatus for injecting coiled tubing strings with a plurality of integrated large diameter external assemblies into wells having positive wellhead pressures.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an installation stack for aiding in the completion of oil and gas wells using coiled tubing.

It is another object of the present invention to an installation stack for injecting coiled tubing strings into wells having positive wellhead pressures.

It is another object of the present invention to provide an installation stack for injecting coiled tubing strings, having external assemblies having a larger outside diameter than the coiled tubing, into wells.

It is another object of the present invention to provide an installation stack for injecting coiled tubing strings, having external assemblies having a larger outside diameter than the coiled tubing, and spaced from a distal end of the coiled tubing.

According to one embodiment of the present invention, a method of installing a coiled tubing string having a plurality of external assemblies includes injecting a coiled tubing string into a well with a coiled tubing injector, when a first external assembly on the coiled tubing string reaches the coiled tubing injector, transferring support of the coiled tubing from the coiled tubing injector to a coiled tubing snubber located below the coiled tubing injector, opening the coiled tubing injector to an extent sufficient to allow passage of the first external assembly thereby, and actuating the coiled tubing snubber to move the first external assembly past the coiled tubing injector. The first external assembly has an outside diameter that is larger than an outside diameter of the coiled tubing string.

According to another embodiment of the present invention, a system for installing a coiled tubing string having a plurality of external assemblies into a well having a positive wellhead pressure includes a coiled tubing injector configured to lower a coiled tubing string into a well, an upper annular blow out preventer located below the coiled tubing injector and receiving the coiled tubing string therefrom, and a coiled tubing snubber located below the upper annular blow out preventer and configured to support the weight of the coiled tubing string when the coil tubing string is not supported by the coiled tubing injector, and to move a first external assembly of the plurality of external assemblies of the coiled tubing string past the coiled tubing injector and the upper annular blow out preventer. The first external assembly has an outside diameter that is larger than an outside diameter of the coiled tubing string.

According to yet another embodiment of the present invention, an assembly for installing a coiled tubing string having a plurality of external assemblies into a well having a positive wellhead pressure is provided. The assembly includes a coiled tubing injector configured to lower a coiled tubing string into a well, an upper annular blow out preventer located below the coiled tubing injector and receiving the coiled tubing string therefrom, a coiled tubing snubber located below the upper annular blow out preventer and configured to support the weight of the coiled tubing string when the coil tubing string is not supported by the coiled tubing injector, and to move a first external assembly of the plurality of external assemblies of the coiled tubing string past the coiled tubing injector and the upper annular blow out preventer, a lower annular blow out preventer located below the coiled tubing snubber, and a pipe/slip ram blow out preventer located below the lower annular blow out preventer. The first external assembly has an outside diameter that is larger than an outside diameter of the coiled tubing string.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:

FIG. 1 is a simplified schematic illustration of a wellhead/well control stack for use with an oil or gas well, according to an embodiment of the present invention.

FIG. 2 is a simplified schematic illustration of a coiled tube string with multiple external assemblies such as packers, etc.

FIG. 3 is a simplified schematic illustration of a wellhead/well control stack for use with an oil or gas well, according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

With reference to FIGS. 1 and 2, the inventive method and related apparatus 10 for injecting coiled tubing strings with a plurality of integrated large diameter external assemblies into wells having positive wellhead pressures will now be described.

If a particular application requires a coiled tubing string that has an outside diameter that is too great to feed through the inner bore of a single or plurality of external assemblies, then that assembly or those assemblies may be integrated into larger diameter coiled tubing by cutting the coiled tubing and welding or mechanically connecting them at the desired locations before the coiled tubing is spooled onto the shipping or installation spools. To successfully spool the coiled tubing with the external assemblies welded in place requires the addition of customized spacer blocks that guide the tubing on both sides of the external assemblies while spooling.

Once spooled, these spacer blocks provide an outer surface that is uniform with the adjacent tubing on either side of the spacer block so when an overlapping layer of tubing is placed above the spacer blocks containing the external assemblies that are integrated into the coiled tubing string the surface remains flush and uniform and therefore preserving the integrity of the spooling process. When installing the string with a plurality of external assemblies into a well with a positive wellhead pressure, the present invention utilizes a number of novel processes and apparatuses that are introduced between the BOPs and the CT injector.

With particular, reference to FIG. 1, the first change to a conventional CT installation assembly by the present invention is to introduce a new apparatus 12 that is analogous to what is commonly known in the oil well servicing industry as a snubbing unit which is used to forcefully insert straight jointed tubing into an oil or gas well having a positive wellhead pressure while maintaining a pressure seal around that tubing during the installation or removal procedures.

A snubbing unit consists of a traveling block and slip assembly that will engage onto a section or “joint” of tubing and forcefully move the tubing string in an upward (out of hole) or downward (in hole) direction using hydraulic rams. The distance of travel is limited to the length of the hydraulic rams. A second stationary block and slip assembly will engage and support the tubing string while the travelling assembly returns to either the upper most position or lower most position depending on whether the procedure is to install or remove the tubing string from the well.

The new apparatus is referred to as a CT Snubber 12 which has the same attributes as a conventional snubbing unit however also incorporates a housing that has a large enough inner bore and sufficient interior length to accommodate the external assemblies that are integrated onto the CT 30. The CT Snubber may also have an exterior housing 14 having a window 16 that will open to expose the CT and/or the external assemblies and therefore allow for the manipulation or addition of components or removal of components to the CT and/or external assemblies. For example, the window may be opened to allow access to the CT and external assembly, so that a protective cover over the external assembly may be removed prior to placement of the external assembly within the well.

A second modification to the conventional CT installation stack by the present invention is to remove the pressure sealing system known as the CT stripper. A third modification is to install two annular BOPs, e.g., BOP 18 and BOP 20, above and below the CT Snubber 12, respectively, that include an oil lubrication system (e.g., a drip lubricator) in order to allow the CT 30 to pass through the two annular BOPs 18, 20 while they are in the closed position.

When starting the CT installation or removal process, this new arrangement of equipment is installed onto the wellhead 22 and the coiled tubing 30 is forcefully inserted into or removed from an oil or gas well conventionally using a CT injector 24. The annular BOPs 18, 20 are both closed and oil lubrication nozzles of the oil lubrication system supply a sufficient volume of lubricant to ensure the BOPs 18, 20 do not become damaged as the CT 30 passes through them. The following procedure is followed when installing a CT string with a single or plurality of external assemblies.

Using the CT injector 24, the CT 30 is injected through the two closed annular BOPs 18, 20, and when the first of a plurality of external assemblies reaches the CT injector 24, a pipe/slip ram BOP 26 located below the lower annular BOP 20 is closed, and the CT Snubber 12 is moved to the uppermost position and closed onto the CT 30 and therefore able to support the weight of the CT string. The CT injector 24 is then opened so that its inner diameter is large enough to allow for the passage of the external assembly through the injector 24. The upper annular BOP 18, which is installed above the CT Snubber 12 and below the CT injector 24, is also opened large enough to allow the passage of the external assembly. As discussed in detail hereinafter, in certain embodiments, the CT Snubber 12 may be a second CT injector having substantially the same configuration as CT injector 24.

The ram BOPs 26 are opened to allow for CT movement, and the CT Snubber 12, which is supporting the full weight of the CT string, is moved hydraulically in a downward direction thereby moving the external assembly through the open injector 24 and open annular BOP 18. This process is repeated until the external assembly is completely contained within the CT Snubber housing 14. Then, the pipe/slip ram BOPs 26 are closed, the injector 24 is closed onto the CT 30 and the annular BOPs 18, 20 are closed. At this point, the full CT string weight is transferred to the injector 24 and the snubbing blocks and slips of the CT Snubber 12 are opened up and returned to the upper position.

The pipe/slip ram BOP 26 and lower annular BOP 20 are opened and the CT 30 and external assembly are slowly lowered through both BOPs 20, 26 using the CT injector 24. When the external assembly is fully past the BOPs 20, 26 the lower annular BOP 20 is closed and the oil lubrication system is activated on both annular BOPs 18, 20. Using the CT injector 24, the CT 30 is lowered into the well until the next external assembly reaches the top of the CT injector 24.

The above steps are repeated until all the external assemblies have been placed into the well at their desired landing locations. The same apparatus 10 may be used for the removal of CT 30 having external assemblies that have a larger outside diameter than the CT 30 by performing the above process in reverse order.

As indicated above, the present invention contemplates the integration of a singular or a plurality of external assemblies onto a CT string whereby the external assemblies have a larger outside diameter than the CT and an inside diameter that is too small to allow for the CT string to pass through. These external assemblies must therefore be integrated onto the CT string prior to spooling the CT string onto the shipping or installation spool. The integration, therefore, requires that the CT string be cut at the location where the external assembly is to be installed and the external assembly may be attached by welding or other mechanical connection.

To successfully spool the coiled tubing with the external assemblies welded in place requires the addition of customized spacer blocks that guide the tubing on both sides of the external assemblies while spooling. Once spooled, these spacer blocks provide an outer surface that is uniform with the adjacent tubing on either side of the spacer block so when an overlapping layer of tubing is placed above the spacer blocks containing the external assemblies that are integrated into the coiled tubing string the surface remains flush and uniform and therefore preserving the integrity of the spooling process.

Moreover, as discussed above, the present invention contemplates an improved CT Snubber 12 that facilitates the installation of external assemblies having a larger outside diameter than the coiled tubing into a well. The CT Snubber 12 is located above conventional ram BOPs (e.g., BOPs 26) and below a conventional CT injector (e.g., CT injector 24) to allow for the installation of CT strings 30 having a singular or plurality of external assemblies that have a larger outside diameter than the CT string. The CT Snubber 12 includes a traveling block and slip assembly that will engage onto the CT and forcefully move the CT string in an upward (out of hole) or downward (in hole) direction using hydraulic rams. The distance of travel is limited to the length of the hydraulic rams. A second stationary block and slip assembly will engage and support the tubing string 30 while the travelling assembly returns to either the upper most position or lower most position depending on whether the procedure is to install or remove the tubing string 30 from the well 22.

The CT Snubber 12 also incorporates a housing 14 that has a large enough inner bore and sufficient interior length to accommodate the external assemblies that are integrated onto the CT 30. The CT Snubber 12 may also have an exterior housing that will open to expose the CT 30 and/or the external assemblies and therefore allow for the manipulation or addition of components or removal of components to the CT 30 and/or external assemblies.

As discussed above, existing installation stacks may be modified to arrive at the present invention by removing the tight tolerance pressure sealing system known as the CT stripper, and installing two annular BOPs (e.g., annular BOPs 18, 20) that have been modified to include an oil lubrication system in order to allow the CT 30 to pass through the two annular BOPs 18, 20 while they are in the closed position. These annular BOPs 18, 20 are installed above and below the CT Snubber 12, as indicated above.

When installing a CT string 30 with a single or plurality of external assemblies, the CT 30 is forcefully inserted through the two closed annular BOPs 18, 20 using a conventional CT injector 24. When the first of a plurality of external assemblies reaches the CT injector 24, the pipe/slip ram BOP 26 is closed, and the CT Snubber 12 is moved to the uppermost position and closed onto the CT 30 and, therefore, able to support the weight of the CT string 30. The CT injector 24 is then opened so that its inner diameter is large enough to allow for the passage of the external assembly through the injector 24. The upper annular BOP 18 which is installed above the CT Snubber 12 and below the CT injector 24 is also opened large enough to allow the passage of the external assembly.

As indicated above, the ram BOPs 26 are opened to allow for CT movement and the CT Snubber 12, which is supporting the full weight of the CT string, is moved hydraulically in a downward direction, thereby moving the external assembly through the open injector 24 and open annular BOP 18. This process is repeated until the external assembly is completely contained within the CT Snubber housing 14. The pipe/slip ram BOPs 26 are then closed, the injector blocks are engaged onto the CT and the annular BOPs 18, 20 are closed. At this point the full CT string weight is transferred to the injector 24 and the snubbing blocks and slips of the CT snubber 12 are open up and returned to the upper position. The pipe/slip ram BOP 26 and lower annular BOP 20 are opened and the CT 30 and external assembly are slowly lowered through both BOPs 20, 26 using the CT injector 24. When the external assembly is fully past the BOPs 20, 26 the lower annular BOP 20 is closed and the oil lubrication system is activated on both annular BOPs 18, 20. Using the CT injector 24, the CT 30 is lowered into the well until the next external assembly reaches the top of the CT injector 24, and the process is repeated

As further described above, the apparatus 10 may also be used for the removal of CT 30 having external assemblies that have a larger outside diameter than the CT 30 by performing the process in claim in reverse order.

Turning to FIG. 2, a coiled tubing string 30 that has been inserted into a well bore using the installation stack assembly 10 of the present invention is shown. As illustrated therein, the string 30 has a plurality of external assemblies 32, 34, 36 attached thereto via attachment assemblies 38, 40, 42, respectively, and is inserted into a casing 44 and liner hanger 46 of a well. The external assemblies may be of any type of external assembly known in the art, including packers and the like, and may be attached to the coiled tubing 30 by any means known in the art. As shown therein, the outside diameter of the external assemblies 32, 34, 36 is greater than the outside diameter of the coiled tubing 30.

As indicated above, the installation stack and method of the present invention facilitates the injection of coiled tubing strings having a plurality of integrated, large diameter external assemblies into wells having positive wellhead pressures.

With reference to FIG. 3, an installation stack assembly 100 according to another embodiment of the present invention is illustrated. As shown therein, the installation stack assembly 100 is substantially the same as the assembly 10 illustrated in FIG. 1, where like reference numerals designate like parts. With the assembly 100, however, the CT snubber is replaced with a second coiled tubing injector 102 located between the upper annular blow out preventer 18 and lower annular blow out preventer 20. The coiled tubing injector 102 may take the form of any injector known in the art and may have substantially the same configuration as CT injector 24. As with snubber 12 of the embodiment shown in FIG. 1, the second coiled tubing injector 102 of assembly 100 functions to support the weight of the CT string and move the CT string in a downward direction to thereby move the external assembly integrated with the CT string through the open injector 24 and open annular BOP 18, in the same manner as discussed above.

Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of this disclosure. 

1. A method of installing a coiled tubing string having a plurality of external assemblies, comprising the steps of: injecting a coiled tubing string into a well with a coiled tubing injector; when a first external assembly on the coiled tubing string reaches the coiled tubing injector, transferring support of the coiled tubing from the coiled tubing injector to a coiled tubing snubber located below the coiled tubing injector; opening the coiled tubing injector to an extent sufficient to allow passage of the first external assembly thereby; and actuating the coiled tubing snubber to move the first external assembly past the coiled tubing injector; wherein the first external assembly has an outside diameter that is larger than an outside diameter of the coiled tubing string.
 2. The method according to claim 1, further comprising the steps of: prior to injecting the coiled tubing string using the coiled tubing injector, closing an upper annular blow out preventer located above the coiled tubing snubber and a lower annular blow out preventer located below the coiled tubing snubber.
 3. The method according to claim 2, further comprising the step of: supplying a lubricant to the upper and lower annular blow out preventers so that the upper and lower annular blow out preventers do not become damaged as the coiled tubing string passes through the upper and lower annular blow out preventers.
 4. The method according to claim 3, further comprising the steps of: when the first external assembly reaches the coiled tubing injector, and prior to transferring support of the coiled tubing string from the coiled tubing injector to the coiled tubing snubber, closing a pipe/slip ram blow out preventer located below the lower annular blow out preventer and moving the coiled tubing snubber to an uppermost position.
 5. The method according to claim 4, further comprising the step of: after transferring support of the coiled tubing string from the coiled tubing injector to the coiled tubing snubber, opening the upper annular blow out preventer to an extent sufficient to allow passage of the first external assembly thereby.
 6. The method according to claim 5, further comprising the step of: after transferring support of the coiled tubing string from the coiled tubing injector to the coiled tubing snubber, opening the pipe/slip ram blow out preventer.
 7. The method according to claim 6, wherein: the step of actuating the coiled tubing snubber includes moving the first external assembly past the upper annular blow out preventer and into a housing of the coiled tubing snubber.
 8. The method according to claim 7, further comprising the step of: when the first external assembly is contained within the housing of the coiled tubing snubber, closing the pipe/slip ram blow out preventer.
 9. The method according to claim 8, further comprising the steps of: when the first external assembly is contained within the housing of the coiled tubing snubber: transferring support of the coiled tubing from the coiled tubing snubber to the coiled tubing injector; and closing the upper and lower annular blow out preventers.
 10. The method according to claim 9, wherein: transferring support of the coiled tubing from the coiled tubing snubber to the coiled tubing injector includes closing the coiled tubing injector on the coiled tubing string and opening the coiled tubing snubber.
 11. The method according to claim 10, further comprising the steps of: opening the pipe/slip ram blow out preventer; and opening the lower annular blow out preventer.
 12. The method according to claim 11, further comprising the step of: after opening the pipe/slip ram blow out preventer and the lower annular blow out preventer, lowering the coiled tubing string through the pipe/slip ram blow out preventer and the lower annular blow out preventer using the coiled tubing injector.
 13. The method according to claim 12, further comprising the step of: when the first external assembly is past the pipe/slip ram blow out preventer and the lower annular blow out preventer, closing the lower annular blow out preventer, and lowering the coiled tubing string into the well using the coiled tubing injector until a second external assembly reaches the coiled tubing injector.
 14. The method according to claim 13, further comprising the step of: after closing the lower annular blow out preventer, and prior to lowering the coiled tubing string, supplying a lubricant to the upper and lower annular blow out preventers.
 15. The method according to claim 1, wherein: the well has a positive wellhead pressure.
 16. The method according to claim 7, wherein: the coiled tubing snubber is a second coiled tubing injector.
 17. A system for installing a coiled tubing string having a plurality of external assemblies into a well having a positive wellhead pressure, comprising: a coiled tubing injector configured to lower a coiled tubing string into a well; an upper annular blow out preventer located below the coiled tubing injector and receiving the coiled tubing string therefrom; and a coiled tubing snubber located below the upper annular blow out preventer and configured to support the weight of the coiled tubing string when the coil tubing string is not supported by the coiled tubing injector, and to move a first external assembly of the plurality of external assemblies of the coiled tubing string past the coiled tubing injector and the upper annular blow out preventer; wherein the first external assembly has an outside diameter that is larger than an outside diameter of the coiled tubing string.
 18. The system of claim 17, further comprising: a lower annular blow out preventer located below the coiled tubing snubber; and a pipe/slip ram blow out preventer located below the lower annular blow out preventer.
 19. The system of claim 18, wherein: the coiled tubing injector, upper annular blow out preventer, lower annular blow out preventer and pipe/slip ram blow out preventer are configured to open to an extent sufficient to allow passage of the first external assembly.
 20. The system of claim 19, wherein: the coiled tubing snubber includes a first traveling block and slip assembly configured to engage a section of the coiled tubing string and forcefully move the tubing string in an upward and downward direction using hydraulic rams, and a second stationary block and slip assembly configured to engage and support the coiled tubing string while the first travelling block and slip assembly returns to either an upper most position or a lower most position.
 21. The system of claim 20, wherein: the coiled tubing snubber has an inner bore large enough to accommodate the first external assembly therein.
 22. The system of claim 21, wherein: the coiled tubing snubber includes an exterior housing having a window that can be opened to expose the coiled tubing and the first external assembly to allow for the manipulation or addition of components or removal of components to the coiled tubing and the first external assembly.
 23. An assembly for installing a coiled tubing string having a plurality of external assemblies into a well having a positive wellhead pressure, comprising: a coiled tubing injector configured to lower a coiled tubing string into a well; an upper annular blow out preventer located below the coiled tubing injector and receiving the coiled tubing string therefrom; and a coiled tubing snubber located below the upper annular blow out preventer and configured to support the weight of the coiled tubing string when the coil tubing string is not supported by the coiled tubing injector, and to move a first external assembly of the plurality of external assemblies of the coiled tubing string past the coiled tubing injector and the upper annular blow out preventer; a lower annular blow out preventer located below the coiled tubing snubber; and a pipe/slip ram blow out preventer located below the lower annular blow out preventer; wherein the first external assembly has an outside diameter that is larger than an outside diameter of the coiled tubing string.
 24. The assembly of claim 23, wherein: the coiled tubing snubber is a second coiled tubing injector. 